1. Field of the Invention
The invention relates to a cooling circuit, in particular for a motor.
2. Description of the Background Art
An overall efficiency of a motor can be increased considerably by the use of previously unused waste heat.
A motor with a drive unit and a device for heat recovery is known from DE 10 2008 053 066 A1. The drive unit has a cooling circuit with a first heat exchanger, which emits heat of a coolant flowing through the cooling circuit to the environment. The device for heat recovery comprises an evaporator that is flowed through by a hot exhaust gas flow. The evaporator is flowed through by a working fluid that is brought to evaporation by the heat of the exhaust gas flow. The gaseous working fluid is fed to an expansion device, from which mechanical energy can be removed. The mechanical energy can be fed directly to the drive train again, for example, or by conversion into electric energy can be used to operate ancillary components. The working fluid flowing out of the expansion device is fed to a second heat exchanger operating as a condenser, which cools the working fluid and converts it into a liquid state. The condenser is coupled to a cooling circuit of the drive unit. A pump guides the liquid working fluid to the evaporator again, in which the working fluid evaporates again and the cycle process begins again. The flow rate of the coolant flow through the condenser and the condensation performance associated therewith fluctuates due to rotational speed changes of the drive unit, for example.
In addition to the embodiment described above, the condenser as is known is also cooled by a separate low-temperature circuit, which, however, requires a high expenditure due to the use of an additional pump, of additional lines and of a further heat exchanger. Furthermore, electrothermal devices for the direct conversion of heat into electric energy are known, which are cooled by an airflow.